1. Field of the Invention
The subject invention is directed generally to retractable aircraft landing gear, and more particularly, to a locking mechanism for preventing a steering collar of a retractable nose landing gear with a shrink shock strut from rotating within the wheel well of an aircraft during flight.
2. Background of the Related Art
Retractable landing gear for aircraft are well known in the art. In general, retractable landing gears include an elongated shock strut having an upper end that is pivotally mounted to the frame of the aircraft about a retraction axis for pivotal displacement between a vertical, downwardly extending, landing and ground support position, and a horizontal, retracted position nested within a wheel well in a lower surface of the aircraft wing or fuselage.
In such landing gears, the shock strut includes telescopically disposed cylinder and piston members defining a pneumatic or hydraulic spring chamber. Pressure within the chamber biases the strut toward a telescopically extended condition. When landing or at rest on the ground, the weight of the aircraft on the landing gear compresses the strut, forcing the strut to a relatively shortened condition, which may be a number of inches shorter than the extended condition. With the aircraft airborne and the landing gears down, the unloaded gears and associated shock struts assume their fully extended position. For sustained flight, the fully extended landing gears are rotated into the retracted position to reside within the wheel wells of the aircraft.
At times, the length of a landing gear may need to be reduced to fit within the wheel well of an aircraft. In such instances a shrink mechanism may be employed to partially stroke the strut so that it can fit in the required space within the wheel well. A particularly well designed shrink shock strut is disclosed in U.S. Patent Application Publication 2010/0096499 to Luce et al., the disclosure of which is incorporated herein by reference in its entirety.
There are problems associated with introducing a shrink shock strut assembly into the nose landing gear of an aircraft. In particular, for nose landing gears, the wheels/tires are typically oriented in the centered (straight ahead) position for retraction and during landing approach. This is accomplished by a set of cams that are attached to the strut cylinder and strut piston of the shock strut. As the gear is stroked during landing, the cams disengage from one another and allow the strut to steer. When the nose landing gear is in a shrunk condition during retraction or while the aircraft is in flight, the centering cams will not be engaged. This will leave the wheels/tires free to rotate about the strut centerline within the wheel well, allowing the possibility that they could become jammed in the wheel well, which would be undesirable.
Therefore, there is a need in the art for a system that can prevent the wheels/tires of a nose landing gear assembly having a shrink shock strut, from freely rotating within the wheel well of an aircraft when the nose landing gear is in a compressed/shrunk condition, retracted within the wheel well of the aircraft.